U.S. patent number 10,845,501 [Application Number 15/346,242] was granted by the patent office on 2020-11-24 for control of electrically operated radiation generators.
This patent grant is currently assigned to SCHLUMBERGER TECHNOLOGY CORPORATION. The grantee listed for this patent is SCHLUMBERGER TECHNOLOGY CORPORATION. Invention is credited to Sicco Beekman, Onur Ozen, David Alan Rose, Matthieu Simon, Christian Stoller, Libo Yang.
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United States Patent |
10,845,501 |
Stoller , et al. |
November 24, 2020 |
Control of electrically operated radiation generators
Abstract
The present disclosure describes a downhole tool including an
electrically operated radiation generator that selectively output
radiation to a surrounding environment based at least in part on
supply of electrical power; and a control system that determines
likelihood of exposing living beings in the surrounding environment
to output radiation by determining whether one or more check
conditions is met; determine that each of the one or more check
conditions is met before instructing the electrically operated
radiation generator to output radiation; and instruct the
electrically operated radiation generator to cease output of
radiation when at least one of the one or more check conditions is
no longer met.
Inventors: |
Stoller; Christian (Sugar Land,
TX), Simon; Matthieu (Clamart, FR), Rose; David
Alan (Sugar Land, TX), Yang; Libo (Katy, TX), Ozen;
Onur (Clamart, FR), Beekman; Sicco (Houston,
TX) |
Applicant: |
Name |
City |
State |
Country |
Type |
SCHLUMBERGER TECHNOLOGY CORPORATION |
Sugar Land |
TX |
US |
|
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Assignee: |
SCHLUMBERGER TECHNOLOGY
CORPORATION (Sugar Land, TX)
|
Family
ID: |
1000005202344 |
Appl.
No.: |
15/346,242 |
Filed: |
November 8, 2016 |
Prior Publication Data
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Document
Identifier |
Publication Date |
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US 20170139074 A1 |
May 18, 2017 |
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Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
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62254664 |
Nov 12, 2015 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
E21B
49/00 (20130101); G01V 5/08 (20130101) |
Current International
Class: |
G01V
5/08 (20060101); E21B 49/00 (20060101) |
References Cited
[Referenced By]
U.S. Patent Documents
Other References
Radtke et al., "A new capture and inelastic spectroscopy tool takes
geochemical logging to the next level", SPWLA 53rd Annual Logging
Symposium, Jun. 16-20, 2012, pp. 1-16. cited by applicant.
|
Primary Examiner: Porta; David P
Assistant Examiner: Malevic; Djura
Attorney, Agent or Firm: Grove; Trevor G.
Parent Case Text
This application claims priority to U.S. Provisional Application
No. 62/254,664, filed on Nov. 12, 2015, the entirety of which is
incorporated herein by reference.
Claims
What is claimed is:
1. A downhole tool, comprising: an electrically operated radiation
generator configured to selectively output radiation to a
surrounding environment based at least in part on supply of
electrical power; and a control system configured to: determine
likelihood of exposing living beings in the surrounding environment
to output radiation by determining whether one or more check
conditions is met; instruct the electrically operated radiation
generator to output radiation after each of the one or more check
conditions is met; and instruct the electrically operated radiation
generator to cease output of radiation when at least one of the one
or more check conditions is no longer met; wherein the control
system allows operation of the tool at the surface only upon
determining that a hardware key verification condition is met and a
barrier interlock condition is met, wherein the hardware key
verification condition is met when an inserted hardware is verified
as associated with an authorized user, and the barrier interlock
condition is met when a barrier interlock at an opening in a
radiation barrier connected with electrically operated radiation
generator is in a closed position; wherein the one or more check
conditions for operation comprise: an interlock key condition,
wherein the interlock key condition is met if an authorized
interlock key is connected to the downhole tool; a start time
condition based at least in part on whether a clock value is
greater than a start time parameter; and a stop time condition
based at least in part on whether the clock value is less than a
stop time parameter.
2. The downhole tool of claim 1, wherein the control system
comprises a downhole control system located in the downhole tool,
wherein the downhole control system is configured to: determine
whether the start time condition is met; determine whether an
operating duration condition is met based at least in part on
whether a duration that radiation is output from the electrically
operated radiation generator is less than an operating duration
parameter; determine whether a battery voltage threshold condition
is met based at least in part on whether a voltage of a battery
configured to supply the electrical power to the electrically
operated radiation generator is greater than a battery voltage
threshold; and determine whether a password verification condition
is met based at least in part on whether a password input to the
control system is associated with an operator authorized to operate
the electrically operated radiation generator.
3. The downhole tool of claim 2, wherein the downhole control
system is configured to: instruct the electrically operated
radiation generator to output radiation after the start time
condition, the stop time condition, the battery voltage threshold
condition, the password verification condition, the interlock key
condition; and instruct the electrically operated radiation
generator to cease output of radiation after the stop time
condition, the operating duration condition, the battery voltage
threshold condition, the password verification condition, the
interlock key condition, or any combination thereof is no longer
met.
4. The downhole tool of claim 2, wherein the downhole control
system is configured to receive the start time parameter, the stop
time parameter, the operating duration parameter, the battery
voltage threshold, the password, or any combination thereof from a
surface control system of the control system.
5. The downhole tool of claim 4, wherein the downhole control
system is configured to receive from the surface control system via
tension pulses on a conveyance line coupled between the downhole
tool and a surface.
6. The downhole tool of claim 1, wherein: the downhole tool
comprises a slick line tool; and the electrically operated
radiation generator comprises an x-ray generator, a neutron
generator, or a gamma ray generator.
7. The downhole tool of claim 1, wherein the one or more check
conditions comprise an operating duration condition based at least
in part on whether a duration that radiation is output from the
electrically operated radiation generator is less than an operating
duration parameter.
8. The downhole tool of claim 1, wherein the one or more check
conditions comprise: a start command condition, wherein the start
command condition is met if a start command is received from a
surface control system; and a stop command condition, wherein the
stop command condition is met if a stop command is received from
the surface control system.
9. The downhole tool of claim 1, wherein the one or more check
conditions comprise a battery voltage threshold condition based at
least in part on whether a voltage of a battery, configured to
supply electrical power to the electrically operated radiation
generator, is greater than a battery voltage threshold.
10. The downhole tool of claim 1, wherein the start time parameter
and the stop time parameter form a time window between the start
time parameter and the stop time parameter, wherein the start time
condition is met and the stop time parameter is met in response to
the clock value within the time window.
11. The downhole tool of claim 1, comprising a power source
configured to travel into a borehole and provide power to the
electrically operated radiation generator.
12. The downhole tool of claim 11, wherein the power source
comprises a battery.
13. A surface operation tool, comprising one or more indicators and
one or more input devices, wherein the one or more indicators are
configured to provide an indication of operational parameters of an
electrically operated radiation generator, and wherein the one or
more input devices are configured to enable inputting of control
commands to the electrically operated radiation generator; wherein
the surface operation tool is configured to control activation of
the electrically operated radiation generator during surface
operations, wherein to control activation of the electrically
operated radiation generator during surface operations, the surface
operation tool is configured to: determine whether a surface
operation tool verification condition is met based at least in part
on whether the surface operation tool is communicatively coupled to
the electrically operated radiation generator and whether the one
or more indicators are operating properly; determine whether a
barrier interlock condition is met based at least in part on
whether an opening of a radiation barrier connected with the
electrically operated radiation generator is in a closed position;
and determine whether a radiation metric threshold condition is met
based at least in part on whether a radiation metric is less than a
radiation metric threshold.
14. The surface operation tool of claim 13, wherein the surface
operation tool is configured to: instruct the electrically operated
radiation generator to output radiation after the surface operation
tool verification condition and the barrier interlock condition;
and instruct the electrically operated radiation generator to stop
output of radiation after the radiation metric threshold condition,
the barrier interlock condition, or any combination thereof is no
longer met.
15. The surface operation tool of claim 13, wherein the one or more
indicators comprise an electronic display, a light bulb, a speaker,
or any combination thereof.
16. The surface operation tool of claim 13, wherein to control
activation of the electrically operated radiation generator during
surface operations, the surface operation tool is configured to:
determine whether a hardware key condition is met based at least in
part on whether a hardware key input to the one or more input
devices is associated with an operator authorized to operate the
electrically operated radiation generator; determine whether an arm
button condition is met based at least in part on whether an arm
button on the surface operation tool is actuated; and determine
whether an emergency stop button condition is met based at least in
part on whether an emergency stop button on the surface operation
tool is actuated.
17. The surface operation tool of claim 13, wherein to control
activation of the electrically operated radiation generator during
surface operations, the surface operation tool is configured to:
determine whether the barrier interlock condition is met based at
least in part on whether the barrier interlock located at the
opening of the radiation barrier is connected; and determine
whether the radiation metric threshold condition is met based at
least in part on whether the radiation metric is less than the
radiation metric threshold.
Description
BACKGROUND
The present disclosure relates generally to electrically operated
radiation generators and, more particularly, to controlling
operation of the electrically operate radiation generators.
This section is intended to introduce the reader to various aspects
of art that may be related to various aspects of the present
techniques, which are described and/or claimed below. This
discussion is believed to be helpful in providing the reader with
background information to facilitate a better understanding of the
various aspects of the present disclosure. Accordingly, it should
be understood that these statements are to be read in this light,
and not as admissions of prior art.
Generally, an electrically operated radiation generator, such as an
x-ray generator, a gamma ray generator, or a neutron generator, may
generate radiation using electrical power on-demand to facilitate
determining characteristics of its surrounding environment. Thus,
electrically operated radiation generators may be used in various
contexts, such as a downhole tool or for material analysis. For
example, in a downhole tool, an electrically operated radiation
generator may facilitate determining porosity of surrounding
formations based at least in part on count (e.g., number of
neutrons or gamma-rays) of radiation and/or mineralogy of
surrounding formations based at least in part on spectrum of
radiation measured by a detector (e.g., scintillator).
To facilitate determining the characteristics, the electrically
operated radiation generator may output high energy radiation into
its surrounding environment. Once output, the high energy radiation
may interact with atoms in the surroundings, for example,
transferring energy to an atom and/or causing the atom to release
one of its neutrons. As such, the electrically operated radiation
generator may be operated to reduce likelihood of emitting
radiation when not properly insulated from living beings, such as
an operator.
BRIEF DESCRIPTION OF THE DRAWINGS
Various aspects of this disclosure may be better understood upon
reading the following detailed description and upon reference to
the drawings in which:
FIG. 1 is a schematic diagram of a drilling system including a
downhole tool with an electrically operated radiation generator, in
accordance with an embodiment;
FIG. 2 is a schematic diagram of a conveyance line system including
a downhole tool with an electrically operated radiation generator,
in accordance with an embodiment;
FIG. 3 is a block diagram of a downhole tool incorporating an
electrically operated radiation generator, in accordance with an
embodiment;
FIG. 4 is a schematic diagram of the electrically operated
radiation generator of FIG. 3, in accordance with an
embodiment;
FIG. 5 is a flow diagram of a process for controlling operation of
the electrically operated radiation generator of FIG. 3 when making
the transition from a standby state to a radiation generator ready
state, in accordance with an embodiment;
FIG. 6 is a flow diagram of a process for controlling operation of
the electrically operated radiation generator of FIG. 3 when making
the transition from a ready state to a radiation generator output
state, in accordance with an embodiment;
FIG. 7 is a flow diagram of a process for controlling operation of
the electrically operated radiation generator of FIG. 3 when in an
output state, in accordance with an embodiment;
FIG. 8 is a block diagram of a surface operation tool used with the
electrically operated radiation generator of FIG. 3, in accordance
with an embodiment;
FIG. 9 is a flow diagram of a process for controlling operation of
the electrically operated radiation generator of FIG. 3 using the
surface operation tool of FIG. 8 when in a standby state and making
the transition to output state, in accordance with an
embodiment;
FIG. 10 is a flow diagram of a process for controlling operation of
the electrically operated radiation generator of FIG. 3 using the
surface operation tool of FIG. 8 when in an output state, in
accordance with an embodiment.
DETAILED DESCRIPTION
One or more specific embodiments of the present disclosure will be
described below. These described embodiments are examples of the
presently disclosed techniques. Additionally, in an effort to
provide a concise description of these embodiments, not all
features of an actual implementation may be described in the
specification. It should be appreciated that in the development of
any such actual implementation, as in any engineering or design
project, numerous implementation-specific decisions will be made to
achieve the developers' specific goals, such as compliance with
system-related and business-related constraints, which may vary
from one implementation to another. Moreover, it should be
appreciated that such a development effort might be complex and
time consuming, but would nevertheless be a routine undertaking of
design, fabrication, and manufacture for those of ordinary skill
having the benefit of this disclosure.
When introducing elements of various embodiments of the present
disclosure, the articles "a," "an," and "the" are intended to mean
that there are one or more of the elements. The terms "comprising,"
"including," and "having" are intended to be inclusive and mean
that there may be additional elements other than the listed
elements. Additionally, it should be understood that references to
"one embodiment" or "an embodiment" of the present disclosure are
not intended to be interpreted as excluding the existence of
additional embodiments that also incorporate the recited
features.
As mentioned above, an electrically operated radiation generator
may generate and output radiation to facilitate determining
characteristics (e.g., porosity and/or mineralogy) of its
surrounding environment. Depending on characteristics to determine,
various types of electrically operated radiation generators may be
used, such as x-ray generators, gamma ray generators, or neutron
generators. Generally, the different types of electrically operated
radiation generators may output different types of radiation. For
example, an x-ray generator may output x-ray radiation, a gamma ray
generator may output gamma ray radiation, and a neutron generator
may output neutron radiation.
Nevertheless, the different types of electrically operated
radiation generators may be operationally similar in certain
aspects. For example, electrical power may be supplied to
accelerate a particle (e.g., ion or electron) toward a target. When
the particle strikes atoms in the target, radiation may be
generated and output. The radiation may then interact with atoms in
the surrounding environment, for example, causing the atoms in the
surrounding environment to output radiation (e.g., neutrons and/or
gamma rays). A detector (e.g., sensor) may then measure count
(e.g., amount), count rate (e.g., amount per unit time), and/or
other properties of the radiation returned from the surrounding
environment. Based at least in part on such measured properties,
characteristics of the surrounding environment, such as porosity
and/or mineralogy, may be determined.
To cause the atoms in the surrounding environment to output
radiation, the electrically operated radiation generator may output
radiation at high energies. For example, a pulsed neutron generator
may output neutrons between about two to fourteen
megaelectron-volts. Due to this high energy, it may be desirable to
operate the electrically operated radiation generator in some
environments and not others. For example, it may be desirable to
output radiation from an electrically operated radiation generator
when living beings are properly shielded from the radiation (e.g.,
downhole or on surface with radiation barrier) and undesirable to
output radiation when living beings are not properly shield from
the radiation (e.g., on the surface with open radiation
barrier).
Accordingly, as will be described in more detail below, the present
disclosure provides techniques to control operation of an
electrically operated radiation generator both sub-surface (e.g.,
downhole) and on the surface based on check conditions to reduce
likelihood of outputting radiation when undesirable. In some
embodiments, a control system may control operation of an
electrically operated radiation generator based on check conditions
that provide an indication of the surrounding environment and/or
when radiation output is desired. In such embodiments, the control
system may automatically determine whether check conditions are met
before instructing the electrically operated radiation generator to
output radiation and instruct the electrically operated radiation
generator to stop outputting radiation when check conditions are no
longer met.
As described above, an electrically operated radiation generator
may be deployed sub-surface (e.g., downhole) in a downhole tool.
Specifically, the electrically operated radiation generator may
output high energy radiation to facilitate determining
characteristics of surrounding sub-surface formations. As described
above, the high energy radiation may interact with atoms in the
sub-surface formation. In some instances, the sub-surface formation
may be sufficient to shield living beings at the surface from high
energy radiation. Thus, the control system may control operation of
the electrically operated radiation generator such that high energy
radiation is output when operation is authorized, determination of
sub-surface formation characteristics is desired, and the
sub-surface formation is sufficient to shield living beings at the
surface.
In some embodiments, communication between the surface (e.g., an
operator) and the downhole tool when deployed may be limited. For
example, in a slickline system, information may be communicated
from the surface to the downhole tool using stimuli sequences
(e.g., tension pulses), but communication of information from the
downhole tool to the surface may be limited. In other words, the
surface may be able to communicate information to the downhole, but
the downhole tool may be unable to communicate information to the
surface.
Accordingly, in some embodiments, the control system may be divided
between a surface control system (e.g., operator) and a downhole
control system to facilitate controlling operation of the
electrically operated radiation generator with reduced
communication between the surface and the downhole tool. In such
embodiments, the surface control system may communicate information
(e.g., control commands, timing parameters, threshold values and/or
a password) to the downhole control system and the downhole control
system may relatively independently control operation of the
electrically operated based on the received information.
To facilitate, the downhole control system may use check conditions
to determine when output of high energy radiation is desirable
based on factors, such as whether operation is authorized,
determination of sub-surface characteristics is desired, and the
sub-surface formation is sufficient to shield living beings at the
surface. In some embodiments, the check conditions may include a
password verification condition, a temperature threshold condition,
a pressure threshold condition, a battery voltage threshold
condition, a start time condition, a stop time condition, an
operating duration condition, a start command condition, a stop
command condition, and an interlock key verification condition.
For example, in such embodiments, the downhole control system may
transition the electrically operated radiation generator from a
standby state to a ready state when the password verification
condition is met, the start time condition is set, the stop time
condition is set, the operating duration condition is set, and the
battery voltage threshold condition is met. As used herein, the
"standby state" is intended to describe when the electrically
operated radiation generator is power off and each of the check
conditions has not yet been set. Additionally, as used herein, the
"ready state" is intended to describe when the electrically
operated radiation generator is power off and each of the check
conditions has been set, but not yet verified. In some embodiments,
the downhole control system may determine that the password
verification condition is met when an input password is verified as
associated with an authorized user and the battery voltage
threshold condition is met when voltage of a battery is greater
than a battery voltage threshold.
Additionally, in such embodiments, the control system may
transition the electrically operated radiation generator from the
ready state to an output state when the start time condition, the
start command condition, the stop time condition, the battery
voltage condition, the interlock key verification condition, the
password verification condition, the temperature threshold
condition, and the pressure threshold condition are met. As used
herein, the "output state" is intended to describe when electrical
power is supplied and radiation is output from the electrically
operated radiation generator 40. In some embodiments, the control
system may determine that the start time condition is met when a
clock value is greater than a start time parameter, the stop time
condition is met when the clock value is not greater than a stop
time parameter, the start command condition is met when a start
command is received, the battery voltage threshold condition is met
when voltage of the battery is greater than the battery voltage
threshold, the password condition is met when the verified password
has not been canceled, the stop command condition has been met when
a stop command has not been received, the pressure threshold
condition is met when a measured pressure is greater than a
pressure threshold, the temperature threshold condition is met when
a measured temperature is greater than a temperature threshold, and
the interlock key verification condition is met when an authorized
interlock key is connected.
Furthermore, in such embodiments, the control system may transition
the electrically operated radiation generator form the output state
back to the standby state when the stop time condition, the
operating duration condition, the battery voltage threshold
condition, the password verification condition, the stop command
condition, the interlock key verification condition, the pressure
threshold condition, or the temperature threshold condition is no
longer met. In some embodiments, the control system may determine
that the stop time condition is no longer met when a clock value is
not less that the stop time parameter, the battery voltage
threshold condition is no longer met when voltage of the battery is
not greater than the battery voltage threshold, the password
condition is no longer met when the verified password has been
canceled, the stop command condition is no longer met when a stop
command has been received, the pressure threshold condition is no
longer met when the measured pressure is not greater than the
pressure threshold, the temperature threshold condition is no
longer met when the measured temperature is not greater than the
temperature threshold, and the interlock key verification condition
is no longer met when the authorized interlock key is
disconnected.
In this manner, the downhole control system may relatively
independently control operation of the electrically operated
radiation generator, which may facilitate reducing communication
between the downhole control system and the surface control system.
In fact, this may be particularly useful when communication
capabilities between the downhole control system and the surface
control system are limited or non-existent, for example, in a
slickline system.
As described above, the present disclosure also provides techniques
for controlling operation of an electrically operated generator
when operated on the surface. In some instances, an electrically
operated radiation generator may be operated on the surface, for
example, during testing and/or calibration. When operated on the
surface, surrounding formations may no longer be present.
Accordingly, a radiation barrier may be placed around the perimeter
of the electrically operated radiation generator to reduce
likelihood of exposing outside living beings to high energy
radiation. Thus, the control system may consider different factors
when operating on the surface compared to operating downhole.
To facilitate managing the different factors, the control system
may use a surface operation tool when operating an electrically
operated radiation generator on the surface. In some embodiments,
the surface operation tool may include visual and/or audio
indicators to provide indications of operational parameters (e.g.,
operating state, radiation metric, and/or threshold values) of the
electrically operated radiation generator. Additionally, in some
embodiments, the surface operation tool may include input devices
(e.g., buttons) to enable communication with the electrically
operated radiation generator form the surface operation tool.
Additionally, to facilitate, the control system may use may use
check conditions to determine when to output of high energy
radiation is desirable based on factors such as, whether operation
is authorized, radiation output is desired (e.g., for testing
and/or calibration), and the radiation barrier is sufficient to
outside shield living beings. In some embodiments, the check
conditions may include a surface operation tool verification
condition, a hardware key verification condition, a barrier
interlock condition, an arm button condition, a radiation metric
threshold condition, and an emergency stop (E-stop) button
condition.
For example, in such embodiments, the control system may transition
the electrically operated radiation generator from the standby
state to the ready state when the surface operation tool
verification condition, the hardware key verification condition,
and the barrier interlock condition are met. In some embodiments,
the control system may determine that the surface operation tool
verification condition is met when the surface operation tool is
communicatively coupled between the control system and the
electrically operated radiation generator and a self-check has
verified proper operation of the surface operation tool.
Additionally, in some embodiments, the control system may determine
that the hardware key verification condition is met when an
inserted hardware is verified as associated with an authorized user
and the barrier interlock condition is met when a barrier interlock
at an opening in the radiation barrier is connected.
Additionally, in such embodiments, the control system may
transition the electrically operated radiation from the ready state
to the output state when the arm button condition is met. In some
embodiments, the surface operation tool may transmit a start
command to the electrically operated radiation generator when an
arm button is actuated. Thus, the control system may determine that
the arm button condition is met when the arm button is actuated
and/or a start command is transmitted to the electrically operated
radiation generator.
Furthermore, in such embodiments, the control system may transition
the electrically operated radiation generator from the output state
back to the standby state when the radiation metric threshold
condition, the barrier interlock condition, and the e-stop button
condition are no longer met. In some embodiments, the surface
operation tool may transmit a stop command to the electrically
operated radiation generator when an arm button is actuated. Thus,
the control system may determine that the radiation metric
threshold condition is no longer met when a resulting radiation
metric is not less than a radiation metric threshold, the interlock
barrier condition is no longer met when the barrier interlock is
disconnected, and the emergency stop button condition is no longer
met when an emergency stop button is actuated and/or a stop command
is transmitted to the electrically operated radiation generator. In
this manner, the control system may use the surface operation tool
to facilitate controlling operation of the electrically operated
radiation generator on the surface.
Electrically Operated Radiation Generators
Since useful for determining characteristics of its surrounding
environment, electrically operated radiation generators may be used
in various contexts, such as resource (e.g., oil and/or gas)
exploration contexts or material analysis contexts. For example, in
resource exploration, an electrically operated radiation generator
may be included in a downhole tool to determine characteristics of
surrounding sub-surface formations, such as porosity and/or
mineralogy. To simplify discussion, the present disclosure will be
described with regard to a downhole tool. However, one of ordinary
skill in the art should appreciate that the techniques described
herein may be applied to use of electrically operated radiation
generators in other contexts.
Even within downhole tools, the implementation of electrically
operated radiation generators may vary. To help illustrate, FIG. 1
describes use in a drilling system 10, which may be used to drill a
well through sub-surface formations 12. In the depicted embodiment,
a drilling rig 14 at the surface 16 may rotate a drill string 18,
which includes a drill bit 20 at its lower end to engage the
sub-surface formations 12. To cool and/or lubricate the drill bit
20, a drilling fluid pump 22 may pump drilling fluid, commonly
referred to as "mud" or "drilling mud," downward through the center
of the drill string 18 in the direction of the arrow 24 to the
drill bit 20. At the drill bit 20, the drilling fluid may then exit
the drill string 18 through ports (not shown). The drilling fluid
may then flow in the direction of the arrows 28 through an annulus
30 between the drill string 18 and the formation 12 toward the
surface 16. In this manner, the drilling fluid may carry drill
cuttings away from the bottom of a borehole 26. Once at the surface
16, the returned drilling fluid may be filtered and conveyed back
to a mud pit 32 for reuse.
Additionally, as depicted, the lower end of the drill string 18
includes a bottom-hole assembly 34 that includes the drill bit 20
along with various downhole tools, such as a
measuring-while-drilling (MWD) tool 36 and a logging-while-drilling
(LWD) tool 38. Generally, the downhole tools (e.g., MWD tool 36 and
LWD tool 38) may facilitate determining characteristics of the
surrounding formation 12. Thus, in some embodiments, the LWD tool
38 may include an electrically operated radiation generator 40,
which outputs radiation into the surrounding formation 12, and one
or more sensors 42, which may measure radiation returned from the
surrounding formation 12, surrounding pressure, and/or surrounding
temperature.
In some embodiments, a control system 44 may control operation of
the LWD tool 38. For example, the control system 44 may instruct
the electrically operated radiation generator 40 when to output
radiation, instruct the electrically operated radiation generator
40 when to cease outputting radiation, receive measurements from
the sensors 42, and/or process the measurements to determine
characteristics of the surrounding environment (e.g., formation
12). In some embodiments, the control system 44 may be included in
the bottom-hole assembly 34. In other embodiments, the control
system 44 may be separate from the bottom-hole assembly 34, for
example, at the surface 16. In other embodiments, a portion of the
control system 44 may be included in the bottom-hole assembly 34
and another portion may be located separate from the bottom-hole
assembly 34. For example, the control system 44 may be divided
between a downhole control system 44A located in the bottom-hole
assembly 34 and a surface control system 44B located at the surface
16.
When at least a portion is separate from the LWD tool 38,
information (e.g., measurements and/or determined characteristics)
may be transmitted to and/or within the control system 44 for
further processing, for example, via mud pulse telemetry system
(not shown) and/or a wireless communication system. Accordingly, in
some embodiments, the LWD tool 38 and/or the control system 40 may
include wireless transceivers 50 to facilitate communicating
information.
To facilitate controlling operation, the control system 44 may
include one or more processors 46 and one or more memory 48. In
some embodiments, the processor 46 may include one or more general
purpose microprocessors, one or more application specific
processors (ASICs), one or more field programmable logic arrays
(FPGAs), or any combination thereof. Additionally, the memory 48
may be a tangible, non-transitory, computer-readable medium that
stores instructions executable by and data to be processed by the
processor 46. Thus, in some embodiments, the memory 48 may include
random access memory (RAM), read only memory (ROM), rewritable
flash memory, hard drives, optical discs, and the like.
In addition to the drilling system 10, an electrically operated
radiation generator 40 may be used in a conveyance line system 52,
as described in FIG. 2. In the depicted embodiment, the conveyance
line system 52 includes a conveyance line assembly 54 suspended in
the borehole via a cable 56. In some embodiments, the conveyance
line system 52 may be a wireline system when the cable 56 is an
armored electrical cable that enables bi-directional communication
between the conveyance line assembly 54 (e.g., the downhole control
system 44A) and the surface control system 44B.
In other embodiments, the conveyance line system 52 may be a
slickline system when the cable 56 is used to support the
conveyance line assembly 54, but does not provide direct
communication between the conveyance line assembly 54 (e.g.,
downhole control system 44A) and the surface control system 44B. In
such embodiments, the surface control system 44B may communicate
with the conveyance line assembly 54 using physical stimuli. For
example, information (e.g., control commands and/or operational
parameters) may be communicated to the conveyance line assembly 54
using tension pulses on the cable 56. An accelerometer located in
the conveyance line assembly 54 may then detect and interpret the
tension pulls to enable communication of information from the
surface control system 44B to the conveyance line assembly 54.
In other embodiments, casing collar locators may be positioned in
the borehole. Thus, when the downhole tool 62 is moved up or down a
sensor 42 in the conveyance line assembly 54 may detect signals
from the surface control system 44B. Additionally, when the
downhole tool is in a riser, the riser may enable acoustic
communications from the surface control system 44B to the downhole
control system 44A. Furthermore, in some embodiments, a magnetic
and/or electric dipole coupling mechanism may provide a
bidirectional wireless communication channel between the surface
control system 44B and the downhole control system 44A.
Besides the radiation generator 40, the conveyance line assembly 54
may further contain one or more gamma ray detectors 68 and/or one
or more neutron detectors 70, each disposed at a different axial
spacing from the radiation generator 40. The radiation generator 40
can be an electrically operated pulsed neutron generator (PNG) to
emit neutron radiations. Shielding (not shown) may be applied
between the radiation generator 40 and the detectors 68, 70 to
reduce direct transmission of neutrons from the radiation generator
40 to the detectors 68, 70. Thus, detected radiation may be
characterized at each of a plurality of distances from the
radiation generator 40, and thus have different lateral response
(depth of investigation) into the formations surrounding the
borehole 26. In some examples, two or more different types of well
logging instrument, each having a different type of source and
different types of corresponding detectors may be included in the
same instrument assembly of "tool string."
The instrument 54 maybe coupled to an armored electrical cable 56
that may be extended into and retracted from the borehole 26. The
borehole 26 may or may not include metal pipe or casing 27 therein.
The cable 56 conducts electrical power to operate the instrument 54
from a surface 31 deployed the surface control system 44B. Signals
from the detectors 68, 70 may be processed by the downhole control
system 44A for transmission along the cable 56 to the surface
control system 44B for recording and/or further processing. Each of
the downhole control system 44A and the surface control system 44B
may include a processor, a memory and/or a computer system as
explained herein.
Although described in relation to a drilling system 10 and a
conveyance line system 52, electrically operated radiation
generators 40 may also be used in other implementations of downhole
tools. For example, an electrically operated radiation generator 40
may be used in a coiled tubing system, a wired drill pipe system,
or the like. Although implementation may vary, operation of an
electrically operated radiation generator 40 may be generally
similar in certain aspects.
To help illustrate, one embodiment of a downhole tool 62 is
described in FIG. 3. In the depicted embodiment, the downhole tool
62 includes an electrically operated radiation generator 40, an
output radiation monitor 64, shielding 66, one or more gamma ray
detectors (e.g., sensors) 68, and one or more neutron detectors
(e.g., sensors) 70. As described above, the electrically operated
radiation generator 40 may generate and output radiation, such as
gamma rays or neutrons, into its surrounding environment. In some
embodiments, characteristics of the surrounding environment may be
determined based at least in part on amount and/or properties
(e.g., energy) of radiation output and/or radiation received from
the environment.
Accordingly, to facilitate determining the characteristics, the
output radiation monitor 64 may monitor amount and/or properties of
radiation output from the electrically operated radiation generator
40. Thus, in some embodiments, the output radiation monitor 64 may
be a plastic scintillator and photomultiplier that primarily
detects unscattered neutrons emitted from the electrically operated
radiation generator 40. In such embodiments, the output radiation
monitor 64 may facilitate determining a count (e.g., number of
neutrons) and/or a count rate (e.g., number of neutrons per unit
time) of radiation (e.g., fast neutrons) output from the
electrically operated radiation generator 40.
As described above, characteristics may be determined based on
interaction between output radiation and atoms in the surrounding
environment. Neutrons emitted by the generator may interact with
the surrounding materials in different ways. They may collide
inelastically with a nucleus and as a result of the interaction the
nucleus or nuclear reaction product may emit one or more gamma rays
(so-called inelastic gamma rays). Output neutrons may collide
elastically with nuclei in the surrounding materials and slow down
to become an epithermal and eventually thermal neutrons. Slow
neutrons may be captured by nuclei and the capture may be followed
by the emission of one or more gamma rays (capture gamma rays).
Generally, the radiation (e.g., neutrons and/or gamma rays) output
from an atom may depend at least in part on properties (e.g.,
atomic number or atomic mass) of the atom. As such, resulting
radiation may indicate type of materials in the surrounding
formation 12.
Accordingly, to facilitate determining the characteristics, the
downhole tool 62 may include one or more radiation detectors, such
as one or more gamma ray detectors 68 and/or one or more neutron
detectors 70. Since characteristics of the surrounding environment
are determined based on radiation received from the surrounding
environment, shielding 66 may be positioned between the
electrically operated radiation generator 40 and the gamma ray
detector 68/neutron detector 70 to reduce likelihood of radiation
internally passing through the downhole tool 62.
Specifically, a gamma ray detector 68 may detect gamma rays (e.g.,
neutron capture gamma rays and/or inelastic gamma rays) that pass
from the surrounding environment (e.g., formation 12) into the
downhole tool 62. In some embodiments, the gamma ray detector 68
may be a scintillator detector that detects gamma rays by emitting
light when a gamma ray interacts with the atoms of its crystal.
Additionally, in some embodiments, the gamma ray detector 68 may be
surrounded by neutron shielding to reduce likelihood of neutrons
entering the gamma ray detector 68. In this manner, the gamma ray
detector 68 may facilitate determining a count (e.g., magnitude of
gamma rays) and/or a count rate (e.g., magnitude of gamma rays per
unit time) of radiation received from its surrounding environment
(e.g., formation 12).
Additionally, a neutron detector 70 may detect neutrons (e.g.,
epithermal and/or thermal neutrons) that pass from the surrounding
environment (e.g., formation 12) into the downhole tool 62. In some
embodiments, the neutron detector 70 may be a gas proportional
detector that detects neutrons based on changes in proportion of
gases caused by received neutrons. Additionally, in some
embodiments, the neutron detector 70 may be surrounded by neutron
shielding depending on type of neutrons to be detected. For
example, an epithermal neutron detector may be surrounded by
thermal neutron shielding to reduce likelihood of thermal neutrons
entering the neutron detector 70. In this manner, the neutron
detector 70 may facilitate determining a count (e.g. number of
neutrons) and/or a count rate (e.g., number of neutrons per unit
time) of radiation received from its surrounding environment (e.g.,
formation 12).
As described above, the downhole tool 62 may have limited external
communication capabilities, for example, in a slickline system. In
such embodiments, operation of the downhole tool 62 may be
relatively self-contained. Accordingly, the downhole tool 62 may
include a downhole control system 44A to relatively independently
control operation of the electrically operated radiation generator
40 and a battery 71 to supply electrical power to the electrically
operated radiation generator 40. As described above, the downhole
control system 44A may control operation by instructing the
electrically operated radiation generator 40 to output high energy
radiation when formation 12 properties are desired and the
surrounding formation 12 sufficiently shield living beings from the
high energy radiation.
To facilitate this, as will be described in more detail below, the
downhole tool 62 may include a clock 72 and one or more sensors 42
(e.g., a temperature sensor 74 and a pressure sensor 76) to
directly measure characteristics of the surrounding environment. In
some embodiments, the downhole control system 44A may use the clock
72 to monitor a start time, a stop time, and/or an operating
duration of the electrically operated radiation generator 40.
Additionally, the downhole control system 44A may use measurements
from the one or more sensors 42 to determine expected location of
the electrically operated radiation generator 40. For example,
since pressure and temperature generally increase as depth
increases, the downhole control system 44A may determine expected
depth of the electrically operated radiation generator 40 based at
least in part on pressure and temperature measurements.
Additionally, as described above, in some embodiments, the downhole
tool 62 may be operated on the surface, for example, during testing
and/or calibration. As will be described in more detail below, a
surface operation tool may be communicatively coupled to the
downhole tool when operated on the surface to facilitate reducing
likelihood of exposing living beings to high energy radiation.
Thus, in such embodiments, the downhole tool 62 may include
input/output (I/O) ports 78 to communicatively couple the downhole
tool 62 to external devices, such as a surface operation tool. For
example, the input/output ports 78 may enable the surface operation
tool to transmit control commands (e.g., start command and/or stop
command) to the downhole tool 62 and the downhole tool 62 to
transmit operational parameters (e.g., output radiation) to the
surface operation tool.
As described above, various types of electrically operated
radiation generators 40 may be used. However, the various types may
be operationally similar in certain aspects. Specifically, the
electrically operated radiation generator 40 may use electrical
power to generate ions and/or electrons and to accelerate the ions
and/or electrons toward a target. Upon striking the target,
radiation may be output from the electrically operated radiation
generator 40. To simplify discussion, the electrically operated
radiation generator 40 will be described as a pulsed neutron
generator (PNG). However, one of ordinary skill the art should
recognize that the techniques described herein may be applied to
other types of electrically operated radiation generators 40.
One example of a pulsed neutron generator 80 is described in FIG.
4. Generally, a pulsed neutron generator 80 includes an ion source
82, an accelerating gap 84, a target 86, and one or more power
supplies 88 (e.g., battery 71), which supplies electrical power to
the ion source 82 and/or the target 86. In the depicted embodiment,
the ion source 82 includes a gas reservoir 90, an ionizer 92, and
an extractor electrode (e.g., grid) 94. Additionally, in the
depicted embodiment, the target 86 includes a target film 96 and a
suppressor electrode 98.
In operation, the gas reservoir 90 may generate hydrogen isotopes
as gas. In some embodiments, when electrical power is supplied from
the power supply 88, a filament may increase in temperature causing
a getter containing hydrogen isotopes (e.g., deuterium and/or
tritium) to release the hydrogen isotopes as gas. As gas is
released, pressure in the gas reservoir 90 may increase causing the
hydrogen isotope gas to flow into the ionizer 92.
The ionizer 92 may then ionize the hydrogen isotope gas received
from the gas reservoir 90. In some embodiments, when electrical
power is supplied from the power supply 88, a cathode may output
electrons. Additionally, when electrical power is supplied from the
power supply 88, an anode may generate an electrical field with the
cathode causing the electrode to flow toward the anode. As the
electrons are pulled toward the anode, the electrons may impact and
excite the hydrogen isotopes, thereby generating positive hydrogen
ions.
The extractor electrode 94 may then extract the hydrogen ions from
the ion source 82 into the accelerating gap 84. In some
embodiments, when electrical power is supplied from the power
supply 88, the extractor electrode 94 may generate an electric
field with the anode that guides the hydrogen ions toward the
acceleration gap 84. The hydrogen ions may then be accelerated in
the accelerating gap 84 toward the target 86. In some embodiments,
when electrical power is supplied by the power supply 88, the
suppressor electrode 98 may generate an electric field with the
extractor electrode 94 that accelerates the hydrogen ions toward
the target film 96.
In some embodiments, the target film 96 may be a thin film of
titanium, scandium or other metal known to form hydrides. In one
non-limiting example, the target layer 96 is a metal hydride such
as titanium hydride containing therefore deuterium and/or tritium.
As such, when the hydrogen ions collide with atoms in the target
film 96, a fusion reaction that releases high energy neutrons
(e.g., 14 MeV) may occur. In other words, the supply of electrical
power may control extraction and acceleration of the hydrogen ions
and, thus, output of radiation from the electrical operated
radiation generator 40. In fact, in some embodiments, the power
supply 88 may pulse the electrical power supplied to the extractor
electrode 94 to generate bursts of neutron radiation. In this
manner, the electrically operated radiation generator 40 may be
operated to control when radiation (e.g., high energy neutrons) is
output to its surroundings (e.g., formation 12).
Downhole Operation
As described above, the control system 44 may control operation of
the electrically operated radiation generator 40 when operated
downhole. In some embodiments, the control system 44 may be divided
between a downhole control system 44A located in the downhole tool
62 and a surface control system 44B located at the surface 16.
Additionally, in some embodiments, communication between the
surface control system 44B and the downhole control system 44A may
be limited when downhole. For example, in a slickline system, the
surface control system 44B may be capable of communicating
information to the downhole control system 44A (e.g., using tension
pulses), but communication of information from the downhole control
system 44A to the surface control system 44B may be limited or
non-existent.
Thus, in such embodiments, the surface control system 44B may
communicate information (e.g., control commands, passwords, timing
parameters, and/or threshold values) to the downhole control system
44A and the downhole control system 44A may control operation of
the electrically operated radiation generator 40 relatively
independently based at least in part on the received information.
For example, the surface control system 44B may communicate a start
command to the downhole control system 44A.
However, due to the limited communication capabilities, the surface
control system 44B may be unaware of the other factors (e.g.,
environmental conditions and/or tool conditions) that may affect
whether desirable to output high energy radiation. Thus, as
described above, the downhole control system may use check
conditions to determine when output of high energy radiation is
desirable based on factors, such as whether operation is
authorized, determination of sub-surface characteristics is
desired, and the sub-surface formation is sufficient to shield
living beings at the surface.
To help illustrate, one embodiment of a process 100 for controlling
operation of an electrically operated radiation generator 40 in the
standby state is described in FIG. 5. Generally, the process 100
includes determining that an electrically operated radiation
generator is in a standby state (process block 102), receiving a
password (process block 104), and determining whether the password
is verified (decision block 106). When the password is verified,
the process 100 includes determining a temperature threshold and a
pressure threshold (process block 108), determining a start time
parameter (process block 110), determining a stop time parameter
(process block 112), and determining a operation duration
parameters (process block 114), determining a battery voltage
threshold (process block 116), and transitioning the electrically
operated radiation generator to a ready state (process block 118).
In some embodiment, the process 100 may be implemented by executing
instructions stored in a tangible, non-transitory,
computer-readable medium, such as memory 48 of the control system
44, using processing circuitry, such as the processor 46 of the
control system 44.
Accordingly, the control system 44 may determine that the
electrically operated radiation generator 40 is in the standby
state (process block 102). In some embodiments, the downhole
control system 44A may determine that the electrically operated
radiation generator 40 is in the standby state when electrical
power is not being supplied from the power supply 88 (e.g., battery
71) and each of the check conditions (e.g., the pressure threshold
condition, the battery voltage threshold condition, the start time
condition, the stop time condition, and/or the operating duration
condition) has not yet been set.
Additionally, the control system 44 may receive a password (process
block 104). In some embodiments, the password may be an
alphanumeric password input to the surface control system 44B
(e.g., by an operator). Once received, the control system 44
determine whether the password verification condition is met by
determining whether the input password is associated with a user
(e.g., operator) authorized to operate the electrically operated
radiation generator 40 (decision block 106). In some embodiments,
the control system 44 may verify the password by determining
whether the password is on a list of passwords associated with
authorized users. Additionally, in some embodiments, the surface
control system 44B may verify the password and inform the downhole
control system 44A that the password verification condition has
been met (e.g., using tension pulses). In other embodiments, the
surface control system 44B may transmit the password to the
downhole control system 44A (e.g., using tension pulses) and the
downhole control system 44A may verify the password.
After the password verification condition is met, the control
system may determine operational parameters used for other check
conditions. For example, the control system 44 may determine a
temperature threshold and a pressure threshold condition based on a
pressure threshold (process block 108). In some embodiments, the
temperature threshold and/or the pressure threshold may be input to
the surface control system 44B (e.g., by an operator) and the
surface control system 44B may transmit the temperature threshold
and/or pressure threshold to the downhole control system 44A (e.g.,
using tension pulses). The downhole control system 44A may then
interpret and store the temperature threshold and/or pressure
threshold in memory 48 for subsequent use, for example, when
determining whether the temperature threshold condition and/or the
pressure threshold condition are met.
As described above, temperature and pressure surrounding the
downhole tool 62 may provide an indication of expected location of
the downhole tool 62. Thus, in some embodiments, the pressure
threshold and/or the temperature threshold may be set at conditions
of a current surface 16 location. In such embodiments, a pressure
and/or a temperature higher than the respective threshold may
indicate that the downhole tool 62 is likely below the surface 16.
On the other hand, a pressure and/or temperature lower than the
respective threshold may indicate that the downhole tool 62 is
likely at the surface 16.
Additionally, the control system 44 may determine the start time
parameter (process block 110). As used herein, the "start time
parameter" is intended to describe an absolute time after which the
electrically operated radiation generator 40 can, but does not
necessarily, begin outputting radiation. In some embodiments, the
start time parameter may be input to the surface control system 44B
(e.g., by an operator) and the surface control system 44B may
communicate the start time parameter to the downhole control system
44A (e.g., using tension pulses). The downhole control system 44A
may then interpret and store the start time parameter in memory 48
for subsequent use, for example, when determining whether the start
time condition is met.
Furthermore, the control system 44 may determine the stop time
parameter (process block 112). As used herein, the "stop time
parameter" is intended to describe an absolute time at which the
electrically operated radiation generator 40 must stop outputting
radiation. In some embodiments, the stop time parameter may be
input to the surface control system 44B (e.g., by an operator) and
the surface control system 44B may communicate the stop time
parameter to the downhole control system 44A (e.g., using tension
pulses). The downhole control system 44A may then interpret and
store the stop time parameter in memory 48 for subsequent use, for
example, when determine whether the stop time condition is met.
The control system 44 may also determine the operating duration
parameter (process block 114). As used herein, the "operating
duration parameter" is intended to describe a relative time during
which the electrically operated radiation generator 40 can, but
does not necessarily, output radiation. In some embodiments, the
operating duration parameter may be input to the surface control
system 44B (e.g., by an operator) and the surface control system
44B may communicate the operating duration parameter to the
downhole control system 44A (e.g., using tension pulses). The
downhole control system 44A may then interpret and store the
operating duration parameter in memory 48 for subsequent use, for
example, when determining whether the operating duration condition
is met.
Additionally, the control system 44 may determine the battery
voltage threshold (process block 116). In some embodiments, the
battery voltage threshold may be predetermined and stored in the
downhole control system 44A before deploying downhole. In other
embodiments, the battery voltage threshold may be input to the
surface control system 44B (e.g., by an operator) and the surface
control system 44B may communicate the battery voltage threshold to
the downhole control system 44A (e.g., using tension pulses). The
downhole control system 44A may then interpret and store the
battery voltage threshold in memory 48 for subsequent use, for
example, when determining whether the battery voltage threshold
condition is met.
Generally, voltage of a battery 71 may decrease as amount of stored
electrical energy decreases. Accordingly, the battery voltage
threshold may be set to indicate whether the amount of electrical
energy stored in the battery 71 is expected to be sufficient to
power the electrically operated radiation generator 40 for an
expected operating duration. Thus, in some embodiments, the battery
voltage threshold may be set based at least in part on the
operating duration parameter.
It should be appreciated that the operational parameters are
described as being determined in a particular order merely to
facilitate description. In other embodiments, the control system 44
may determine the operational parameters in any order and/or in
parallel. Additionally, in other embodiments, the control system 44
may determine other operational parameters used to determine
whether other check conditions are met.
Once one or more of the operational parameters to be used for check
conditions are determined, the control system 44 may transition the
electrically operated radiation generator 40 to the ready state
(process block 118). In the ready state, the control system 44 may
determine whether output of high energy radiation is desirable by
determining whether each of the check conditions is met.
To help illustrate, one embodiment of a process 124 for controlling
operation of an electrically operated radiation generator 40 in the
ready state is described in FIG. 6. Generally, the process 124
includes determining that an electrically operated radiation
generator is in a ready state (process block 126), determining a
first clock value (process block 128), determining whether the
clock value is greater than a start time parameter (decision block
130), receiving a start command after the clock value is greater
than the start time parameter (process block 132), determining a
second clock value (process block 133), determining whether the
clock value is less than a stop time parameter (decision block
134), determining voltage of a battery (process block 136),
determining whether voltage of the battery is less than a threshold
(decision block 138), determining whether a password is canceled
(decision block 140), determining whether a stop command is
received (decision block 142), determining whether an interlock key
is connected (decision block 144), determining a pressure
measurement (process block 146), determining whether the pressure
measurement is greater than a threshold (decision block 148),
determining a temperature measurement (process block 150), and
determining whether the temperature measurement is greater than a
threshold (decision block 152).
When the voltage is greater than the voltage threshold, the
password has not been canceled, the stop command has not been
received, the downhole interlock is connected, the pressure
measurement is greater than the threshold, the temperature
measurement is greater than the threshold, and the second clock
value is less than the stop time parameter, the process 124
includes transitioning the electrically operated radiation
generator 40 to an output state (process block 154) and, otherwise,
transitioning the electrically operated radiation generator 40 to a
standby state (process block 156). In some embodiment, the process
124 may be implemented by executing instructions stored in a
tangible, non-transitory, computer-readable medium, such as memory
48 of the control system 44, using processing circuitry, such as
the processor 46 of the control system 44.
Accordingly, the downhole control system 44A may determine that the
electrically operated radiation generator 40 is in the ready state
(process block 126). In some embodiments, the downhole control
system 44A may determine that the electrically operated radiation
generator 40 is the ready state when electrical power is not being
supplied from the power supply 88 (e.g., battery 71) to the
electrically operated radiation generator 40 and each of the
operational parameters used for the check conditions has been
determined.
As described above, in the ready state, the downhole control system
44A may determine whether check conditions are met. For example,
the downhole control system 44A may determine whether the start
time condition is met by determining the first clock value (process
block 128) and determining whether the first clock value is greater
than the start time parameter (decision block 130). In some
embodiments, the downhole control system 44A may determine the
clock value by polling the clock 72. Additionally, the downhole
control system 44A may retrieve the start time parameter from
memory 48 and compare it with the first clock value.
As described above, the start time parameter may be the earliest
time that the electrically operated radiation generator can begin
outputting radiation. Thus, when the clock value is not greater
than the start time parameter, the downhole control system 44A
determine that the start time condition it not yet met and
periodically recheck if the first clock value is greater than the
start time parameter (arrow 157).
Once the clock value becomes greater than the start time parameter,
the downhole control system 44A may determine that the start time
condition is met and determine whether a start command condition is
met by determining whether a start command has been received
(process block 132). In some embodiments, the start command may be
input to the surface control system 44B (e.g., by an operator) to
indicate that determination of a formation 12 property is desired.
As such, the surface control system 44B may transmit the start
command to the downhole control system 44A (e.g., using tension
pulses).
Once the start command is received, the downhole control system 44A
may determine that the start command condition is met and then
determine whether other check conditions are met. For example, the
downhole control system 44A may determine whether the stop time
condition is met by determining a second clock value (process block
133) and determining whether the second clock value is less than
the stop time parameter (decision block 134). In some embodiments,
the downhole control system 44A determines the second block value
by polling the clock 72. Additionally, the downhole control system
44A may retrieve the stop time parameter from memory 48 and compare
it with the second clock value.
As described above, the stop time parameter may indicate time that
the electrically operated radiation generator must cease outputting
radiation. Thus, when the second clock is less than the stop time
parameter, the downhole control system 44A may determine that the
stop time parameter is met. On the other hand, when the second
clock is not less than the stop time parameter, the downhole
control system 44A may determine that the stop time parameter is
not met and transition the electrically operated radiation
generator 40 back to the standby state (process block 156).
Additionally, the downhole control system 44A may determine whether
the battery voltage threshold condition is met by determining
voltage of the battery 71 (process block 136) and determining
whether the voltage of the battery 71 is greater than the battery
voltage threshold (decision block 138). In some embodiments, the
downhole control system 44A may determine the voltage of the
battery 71 by polling a voltage sensor 42 connected to a terminal
of the battery 71. Additionally, the downhole control system 44A
may retrieve the battery voltage threshold from memory 48 and
compare the voltage of the battery 71 to the battery voltage
threshold.
As described above, the battery voltage threshold may indicate
minimum amount of electrical energy stored to enable the battery 71
to power the electrically operated radiation generator 40. Thus,
when the voltage of the battery 71 is greater than the battery
voltage threshold, the downhole control system 44A may determine
that the battery voltage threshold condition is met. On the other
hand, when the voltage of the battery 71 is not greater than the
battery voltage threshold, the downhole control system 44A may
determine that the battery voltage threshold condition is not met
and transition the electrically operated radiation generator 40
back to the standby state (process block 156).
The downhole control system 44A may also determine whether the
interlock key verification condition is met by determining whether
the interlock key is connected (decision block 144). In some
embodiments, the interlock key may be a dedicated component that is
selectively connected and disconnected from the conveyance line
assembly 54. In some embodiments, the interlock key may be a
resistor with a specific value. In such embodiments, the downhole
control system 44A may determine whether an authorized interlock
key is connected by using a sensor 42 to measure resistance across
a slot for the interlock key.
In some embodiments, the interlock key may provide hardware
authorization for operation of the electrically operated radiation
generator 40. Thus, when an authorized interlock key is connected,
the downhole control system 44A may determine that the interlock
key verification condition is met. On the other hand, when an
authorized interlock key is not connected, the downhole control
system 44A may determine that the interlock key verification
condition is not met and transition the electrically operated
radiation generator 40 back to the standby state (process block
156).
Furthermore, the downhole control system 44A may determine whether
the pressure threshold condition is met by determining the measured
pressure of the surrounding environment (process block 146) and
determining whether the measured pressure is greater than the
pressure threshold (decision block 148). In some embodiments, the
downhole control system 44A may determine the measured pressure by
polling the pressure sensor 76. Additionally, the downhole control
system 44A may retrieve the pressure threshold from memory 48 and
compare the measured pressure to the pressure threshold.
As described above, the pressure threshold may be set at the
pressure at or near the surface 16. In other words, measured
pressure greater than the pressure threshold may indicate that the
downhole tool 62 is likely downhole. Thus, when the measured
pressure is greater than the pressure threshold, the downhole
control system 44A may determine that the pressure threshold
condition is met. On the other hand when the measured pressure is
not greater than the pressure threshold, the downhole control
system 44A may determine that the pressure threshold condition is
not met and transition the electrically operated radiation
generator 40 back to the standby state (process block 156).
The downhole control system 44A may also determine whether the
temperature threshold condition is met by determining the measured
temperature of the surrounding environment (process block 150) and
determining whether the measured temperature is greater than the
temperature threshold (decision block 152). In some embodiments,
the downhole control system 44A may determine the measured
temperature by polling the temperature sensor 74. Additionally, the
downhole control system 44A may retrieve the temperature threshold
from memory 48 and compare the measured temperature to the
temperature threshold.
As described above, the temperature threshold may indicate
temperature at or near the surface 16. In other words, measured
temperature greater than the temperature threshold may indicate
that the downhole tool 62 is likely downhole. Thus, when the
measured temperature is greater than the temperature threshold, the
downhole control system 44A may determine that the temperature
threshold condition is met. On the other hand when the measured
temperature is not greater than the temperature threshold, the
downhole control system 44A may determine that the temperature
threshold condition is not met and transition the electrically
operated radiation generator 40 back to the standby state (process
block 156).
In some embodiments, there may be more than one temperature sensor
or more than one pressure sensor. In such embodiments, one may
avoid the undesirable situation where a defective sensor causes a
shutdown of the radiation generator. Instead of relying on the
output of only one sensor, the decision may be based on whether a
majority of the sensors indicate that the condition to generate
radiation is met, or in a stricter scenario, whether more than a
predetermined number of sensors indicate an undesired condition. In
some embodiments, outputting radiation may not be allowed if more
than one of the sensors (e.g. temperature or pressure sensors) is
reading a value that is inconsistent with the readings of the
remaining sensors. Additionally, the downhole control system 44A
may determine whether the password verification condition is still
met by determining whether the verified password has been canceled
(decision block 140). In some embodiments, cancellation of the
verified password may be input to the surface control system 44B
(e.g., by an operator) and the surface control system 44B may
transmit an indication of the cancellation to the downhole control
system 44A (e.g., using tension pulses).
As described above, the password may be verified to provide
software authorization to operate the electrically operated
radiation generator 40. Thus, when the verified password has not
been a canceled, the downhole control system 44A may determine that
the password verification condition is still met. On the other
hand, when the verified password has been canceled, the downhole
control system 44A may determine that the password verification
condition is no longer met and transition the electrically operated
radiation generator 40 back to the standby state (process block
156).
The downhole control system 44A may also determine whether the stop
command condition is met by determining whether a stop command has
been received (decision block 142). In some embodiments, a stop
command may be input to the surface control system 44B (e.g., by an
operator) and surface control system 44B may transmit the stop
command to the downhole control system 44A (e.g., using tension
pulses). Generally, the stop command may be input to indicate that
subsequent radiation output is not desired. Thus, when a stop
command has not been received, the downhole control system 44A may
determine that the stop command condition is met. On the other
hand, when a stop command has been received, the downhole control
system 44A may determine that the stop command condition is not met
and transition the electrically operated radiation generator 40
back to the standby state (process block 156).
It should be appreciated that the downhole control system 44A is
described as determine whether each of the check conditions in a
particular order merely to facilitate description. In some
embodiments, the downhole control system 44A may determine whether
the check conditions are met in any order. In some embodiments, the
downhole control system 44A may simultaneously determine whether a
plurality of check conditions is met. Additionally, in other
embodiments, the downhole control system 44A may determine whether
other check conditions are met.
When each of the check conditions is met, the downhole control
system 44A may transition the electrically operated radiation
generator 40 to an output state (process block 154). Once in the
output state, the downhole control system 44A may continue
determining whether each of the check conditions continue to be
met. When one or more check condition is no longer met, the
downhole control system 44A may instruct the electrically operated
radiation generator 40 to cease output of radiation.
To help illustrate, one embodiment of a process 158 for controlling
operation of an electrically operated radiation generator 40 in the
output state is described in FIG. 7. Generally, the process 158
includes determining that a electrically operated radiation
generator is in an output state (process block 160), determining a
first clock value (process block 161), instructing the electrically
operated radiation generator to output radiation (process block
162), determining a second clock value (process block 164),
determining whether the second clock value is less than a stop time
parameter (decision block 166), determining an operating duration
(process block 168), determining whether the operating duration is
less than an operating duration threshold (decision block 170),
determining voltage of a battery (process block 172), determining
whether the voltage of the battery is greater than a threshold
(decision block 174), determining whether a password is canceled
(decision block 176), determining whether a stop command is
received (decision block 178), determining whether an interlock key
is connected (decision block 180), determining a pressure
measurement (process block 182), determining whether the pressure
measurement is greater than a threshold (decision block 184),
determining a temperature measurement (process block 186), and
determining whether the temperature measurement is greater than a
threshold (decision block 188).
When the voltage is greater than the voltage threshold, the
password has not been canceled, the stop command has not been
received, the downhole interlock is connected, the pressure
measurement is greater than the threshold, the temperature
measurement is greater than the threshold, and the clock value is
less than the stop time parameter, the process 158 includes
maintaining the electrically operated radiation generator 40 in the
output state (arrow 190) and, otherwise, transitioning the
electrically operated radiation generator 40 to a standby state
(process block 192). In some embodiment, the process 158 may be
implemented by executing instructions stored in a tangible,
non-transitory, computer-readable medium, such as memory 48 of the
control system 44, using processing circuitry, such as the
processor 46 of the control system 44.
Accordingly, the downhole control system 44A may determine that the
electrically operated radiation generator 40 is in the output state
(process block 160). When in the output state, the downhole control
system 44A may instruct the electrically operated radiation
generator 40 to output radiation by instructing the power supply 88
(e.g., battery 71) to supply electrical power to the electrically
operated radiation generator 40 (process block 162). Thus, the
downhole control system 44A may determine that the electrically
operated radiation generator 40 is in the output state when
electrical is supplied from the power supply to the electrically
operated radiation generator 40 and/or when the output radiation
monitor 64 detects radiation output from the electrically operated
radiation generator 40.
Additionally, the downhole control system 44A may determine the
first clock value when the electrically operated radiation
generator 40 initially begins outputting radiation (process block
162). In this manner, the first clock value may indicate when the
electrically operated radiation generator 40 is transitioned into
the output state. In some embodiments, the downhole control system
44A may determine the first clock value by polling the clock
72.
As described above, in the output state, the downhole control
system 44A may determine continuously and/or periodically determine
whether check conditions continue to be met. For example, the
downhole control system 44A may determine whether the operating
duration condition is met by determining the second clock value
(process block 164), determining an operating duration of the
electrically operated radiation generator (process block 168) and
determining whether the operating duration is less than the
operating duration parameter (decision block 170). In some
embodiments, the downhole control system 44A may determine the
operating duration by determining difference between the first
clock value and the second clock value. Additionally, downhole
control system 44A may retrieve the operating duration parameter
from memory 48 and compare it with the operating duration.
As described above, the operating duration parameter may indicate
relative duration the electrically operated radiation generator 40
can operate. Thus, when the operating duration is less than the
operating duration parameter, the downhole control system 44A may
determine that the operating duration condition is met. On the
other hand, when the operating duration is not less than the
operating duration parameter, the downhole control system 44A may
determine that the operating duration parameter is no longer met
and transition the electrically operated radiation generator 40
back to the standby state by instructing the power supply 88 (e.g.,
battery 71) to stop supplying electrical power to the electrically
operated radiation generator 40 (process block 192).
Similar to when in the ready state, the downhole control system 44A
may also determine whether the stop time condition is met by
determining whether the second clock value is less than the stop
time parameter (decision block 166). Additionally, the downhole
control system 44A may determine whether battery voltage threshold
condition is met by determining whether the voltage of the battery
71 is greater than the battery voltage threshold (decision block
174) and determining whether the interlock key verification
condition is met by determining whether an authorized interlock key
is connected (decision block 180). Furthermore, the downhole
control system 44A may determine whether the pressure threshold
condition is met by determining whether the measured pressure is
greater than the pressure threshold (decision block 184) and
whether the temperature threshold condition is met by determining
whether the measured temperature is greater than the temperature
threshold (decision block 188). Moreover, the downhole control
system 44A may determine whether check conditions on control
commands are met by determining whether the verified password is
canceled (decision block 176) and whether a stop command has been
received (decision block 142).
When any of the check conditions is not met, the downhole control
system 44A may transition the electrically operated radiation
generator 40 back to the standby state by instructing the power
supply 88 (e.g., battery 71) to stop supplying electrical power to
the electrically operated radiation generator 40 (process block
192). On the other hand, when each of the check conditions is met,
the downhole control system 44A may maintain the electrically
operated radiation generator 40 in the output state to continue
outputting radiation (arrow 190).
It should be appreciated that the downhole control system 44A is
described as determining whether each of the check conditions in a
particular order merely to facilitate description. In other
embodiments, the downhole control system 44A may determine whether
the check conditions are met in any order and/or in parallel.
Additionally, in other embodiments, the downhole control system 44A
may determine whether other check conditions are met.
In this manner, the techniques described herein enable the control
system 44 to control operation of an electrically operated
radiation generator 40 when operated downhole based at least in
part on check conditions. Specifically, the check conditions may be
set so that risk of exposing living beings to high energy radiation
may be reduced when each of the check conditions is met. In fact,
the techniques described herein enable the control system 44 to
relatively independently control operation of the electrically
operated radiation generator 40 even with limited communication
capabilities with the surface 16.
In other embodiments, other techniques may be used to controlling
operation of an electrically operated radiation generator 40 with
limited capabilities with the surface. For example, a magnet switch
inside the downhole tool 62 may be activated by bringing a strong
magnet next to the downhole tool 62. This switch may short-circuit
the battery 71 and force an internal fuse to disconnect, thereby
disconnecting electrical power from the electrically operated
radiation generator 40. Additionally, in some embodiments, the
downhole tool 62 may record pressure gradient while going down and
use this information to determine when it is going back uphole and
automatically stop output of radiation from the electrically
operated radiation generator 40. Furthermore, in some embodiments,
the downhole tool 62 may include a pressure activated mechanical
switch, which would turn the power to the radiation generator OFF,
for example, below a certain pressure (e.g. 1 bar for tool-in-air
conditions). In still further embodiments, the downhole tool 62 may
include tool-in air detection and/or real-time depth detection.
Surface Operation
As described above, the control system 44 may also control
operation of the electrically operated radiation generator 40 when
operated on the surface. When operated sub-surface (e.g.,
downhole), surrounding formations 12 may absorb and, thus, shield
living beings from high energy radiation. However, when operated on
the surface, the electrically operated radiation generator 40 may
instead by surrounded by air, which is much less capable of
absorbing high energy radiation. Thus, risk of exposing living
beings to high energy radiation may increase when operated on the
surface.
As such, the control system 44 may utilize a surface operation tool
to help manage the added risk of operating the electrically
operated radiation generator 40 on the surface. In some
embodiments, the surface operation tool may include visual and/or
audio indicators to provide indications of operational parameters
(e.g., operating state, radiation metric, and/or threshold values)
of the electrically operated radiation generator. Additionally, in
some embodiments, the surface operation tool may include input
devices (e.g., buttons) to enable communication with the
electrically operated radiation generator form the surface
operation tool.
To help illustrate, one embodiment of a surface operation tool 194
used with the control system 44 and the electrically operated
radiation generator 40 is described in FIG. 8. As in the depicted
embodiment, the surface operation tool 194 may be communicatively
coupled between the control system 44 and the radiation generator
40. In this manner, the surface operation tool 194 may receive
information (e.g., control commands and/or operating state of the
electrically operated radiation generator 40) from the control
system 44. Additionally, the surface may transmit control commands
to the electrically operated radiation generator 40.
Additionally, as in the depicted embodiment, the surface operation
tool 194 may be communicatively coupled to one or more sensors 42.
In some embodiments, a sensor 42 may be located in or proximate the
electrically operated radiation parameter to measure a radiation
metrics, such as a count (e.g., amount of output radiation) or a
count rate (e.g., amount of output radiation per unit time), and/or
environmental parameters, such as surrounding pressure or
temperature. In this manner, the surface operation tool 194 may
receive operational parameters from the one or more sensor 42.
Furthermore, as in the depicted embodiment, the surface operation
tool 194 may be communicatively coupled to a barrier interlock 196.
As described above, when operating on the surface 16, air may be
insufficient to shield living beings from exposure to high energy
radiation. Accordingly, in some embodiments, a radiation barrier
may be formed around the perimeter of the electrically operated
radiation generator 40 to shield living beings outside of the
radiation barrier. To provide access to the electrically operated
radiation generator 40, an opening (e.g., a door) may be included
in the radiation barrier. Thus, the barrier interlock 196 may be
located at the opening to monitor whether the opening is open or
closed. In this manner, the surface operation tool 194 may receive
status of the radiation barrier from the barrier interlock 196.
As described above, the surface operation tool 194 may provide
visual indications of various parameters. Accordingly, the surface
operation tool 194 may include one or more visual indicators 198,
such as electronic displays or light bulbs. For example, when an
electronic display, a visual indicator 198 may display an
alphanumeric representation of the output radiation and/or
operating state of the electrically operated radiation generator
40. When a light bulb, a visual indicator 198 may change colors
and/or illuminate in different patterns to indicate an operating
state of the electrically operated radiation generator 40.
Additionally, as described above, the surface operation tool 194
may provide audio indications of various operational parameters.
Accordingly, the surface operation tool 194 may include one or more
audio indicators 200, such as speakers. For example, when a
speaker, an audio indicator 200 may output different sounds and/or
different source patterns to indicate operating state and/or
changes in operating state of the electrically operated radiation
generator 40.
Furthermore, as described above, the surface operation tool 194 may
provide input devices to enable user inputs (e.g., control
commands) to the electrically operated radiation generator 40 from
the surface operation tool 194. Accordingly, the surface operation
tool 194 may include a hardware key slot 202, an emergency stop
(E-stop) button 206, and an arm button 204. In some embodiments, a
hardware key may be inserted into the key slot 202 and the surface
operation tool 194 may determine whether operators associated with
the inserted hardware key have authorization to operate the
electrically operated radiation generator 40. Additionally, the
surface operation tool 194 may transmit a stop command to the
electrically operated radiation generator 40 when the emergency
stop button 206 is actuated and may transmit a start command to the
electrically operated radiation generator 40 when the arm button
204 is actuated.
In this manner, the control system 44 may use the surface operation
tool 194 to facilitate controlling operation of the electrically
operated radiation generator 40. Specifically, the surface
operation tool 194 may reduce likelihood of exposing living beings
to high energy radiation by providing quick access to the
electrically operated radiation generator 40, for example, by
enabling operators to determine operational parameters from the
surface operation tool 194 and/or to input control commands to the
electrically operated radiation generator from the surface
operation tool 194. Additionally, as described above, the control
system 44 may control operation of the electrically operated
radiation generator 40 based on check conditions to reduce
likelihood of exposing living beings to high energy radiation.
To help illustrate, one embodiment of a process 208 for controlling
operation of an electrically operated radiation generator 40 when
in the standby state is described in FIG. 9. Generally, the process
208 includes determining that a radiation generator is in a standby
state (process block 210), indicating the standby state (process
block 212), determining whether a surface operation tool is
connected (decision block 214), performing a self-check on the
surface operation tool (process block 216), determining whether the
surface operation tool is operating properly (decision block 218),
determining whether a hardware key is verified (decision block
220), determining status of a barrier interlock (process block
222), indicating status of the barrier interlock (process block
224), and determining whether the barrier interlock is connected
(decision block 226).
When the surface operation tool is connected, the hardware key is
verified, the surface operation tool is operating properly, and the
barrier interlock is connected, the process 208 includes
transitioning the electrically operated radiation generator to a
ready state (process block 228) and, otherwise, maintaining the
electrically operated radiation generator in the standby state
(arrow 230). When in the ready state, the process 208 includes
indicating the ready state (process block 232) and determining
whether an arm button is actuated (decision block 234). When the
arm button is actuated, the process 208 includes transitioning the
electrically operated radiation generator to an output state
(process block 236) and indicating the output state (process block
238). In some embodiment, the process 208 may be implemented by
executing instructions stored in a tangible, non-transitory,
computer-readable medium, such as memory 48 of the control system
44, using processing circuitry, such as the processor 46 of the
control system 44.
Accordingly, the control system 44 may determine that the
electrically operated radiation generator 40 is in the standby
state (process block 210). In some embodiments, the downhole
control system 44A may determine that the electrically operated
radiation generator 40 is in the standby state when electrical
power is not being supplied from the power supply 88 and each of
the check conditions (e.g., the pressure threshold condition, the
battery voltage threshold condition, the start time condition, the
stop time condition, and/or the operating duration condition) has
not yet been considered.
Additionally, the control system 44 may instruct the surface
operation tool 194 to indicate that the electrically operated
radiation generator 40 is in the standby state (process block 212).
In some embodiments, the surface operation tool 194 may indicate
the standby state using the visual indicators 198 and/or the audio
indicators 200. For example, the surface operation tool 194 may
indicate the standby state by turning a light bulb visual indicator
198 green and/or displaying an alphanumeric representation on an
electronic display visual indicator 198.
In the standby state, the downhole control system 44A may determine
whether check conditions are met. For example, the control system
44 may then determine whether the surface operation tool
verification condition is met by determining whether the surface
operation tool 194 is communicatively coupled between the control
system 44 and the electrically operated radiation generator 40
(decision block 214), instructing the surface operation tool to
perform a self-check (process block 216), and determining whether
the surface operation tool is operating properly (decision block
218). In some embodiments, the surface operation tool 194 may be
declared in the control system 44 (e.g., by an operator) and the
control system 44 may determine whether the surface operation tool
194 is connected by determining whether signals are received. As
described above, the surface operation tool 194 may facilitate
surface operation by providing indications of various operational
parameters and/or input devices. Accordingly, when the surface
operation tool 194 is not connected, the control system 44 may
determine that the surface operation tool verification condition is
not met and maintain the electrically operated radiation generator
40 in the standby mode (arrow 230).
Additionally, in some embodiments, the surface operation tool 194
may perform the self-check by operating each of the visual
indicators 198 and each of the audio indicators 200 to very that
they are operating properly. When not operating properly, the
control system 44 may determine that the surface operation tool
verification condition is not met and maintain the electrically
operated radiation generator 40 in the standby mode (arrow
230).
When the surface operation tool is connected and the operating
properly, the control system 44 may determine that the surface
operation tool verification condition is met and continue
determining whether other check conditions are met. For example,
the control system 44 may instruct the surface operation tool 194
to check whether the hardware key verification condition is met by
determining whether a hardware key is inserted into the hardware
key slot 202 is associated with an operator authorized to operate
the electrically operated radiation generator 40 (decision block
220). In some embodiments, the surface operation tool 194 may read
information (e.g., shape) from the hardware key and determining
whether the information is on a list associated with authorized
users.
In some embodiments, the hardware key may provide hardware
authorization for operation of the electrically operated radiation
generator 40. Thus, when an inserted hardware key is authorized,
the control system 44 may determine that the hardware key
verification condition is met. On the other hand, when an inserted
hardware key is not authorized, the control system 44 may determine
that the hardware key verification condition is not met and
maintain the electrically operated radiation generator 40 in the
standby mode (arrow 230). Each hardware key may additionally be
associated with a specific password that needs to be entered in
order to meet the hardware key condition.
Additionally, the control system 44 may determine whether the
barrier interlock condition is met by determining status of the
barrier interlock 196 (process block 222) and determining whether
the barrier interlock is connected (decision block 226). In some
embodiments, the barrier interlock 196 may form a circuit when
connected. Thus, the control system 44 may determine whether
connected by polling the barrier interlock 196 to determine whether
the circuit has been formed.
As described above, the barrier interlock 196 may connected at the
opening of a radiation barrier. In other words, the barrier
interlock 196 may be disconnected when the radiation barrier is
open and connected when the radiation barrier is closed. Thus, when
connected, the control system 44 may determine that the barrier
interlock condition is met. On the other hand, when not connected,
the control system may determine that the barrier interlock
condition is not met and maintain the electrically operated
radiation generator 40 in the standby mode (arrow 230).
The control system 44 may also instruct the surface operation tool
194 to indicate status of the barrier interlock 196 (process block
224). In some embodiments, the surface operation tool 194 may
indicate whether the barrier interlock 196 and, thus, the radiation
barrier is open or closed by displaying an alphanumeric
representation on an electronic display visual indicator 198.
It should be appreciated that the control system 44 is described as
determine whether each of the check conditions in a particular
order merely to facilitate description. In other embodiments, the
control system 44 may determine whether the check conditions are
met in any order and/or in parallel. Additionally, in other
embodiments, the downhole control system 44A may determine whether
other check conditions are met.
When each of the check conditions is met, the control system 44 may
transition the electrically operated radiation generator 40 to the
ready state (process block 228) and instruct the surface operation
tool 194 to indicate that the electrically operated radiation
generator 40 is in the ready state (process block 232). In some
embodiments, the surface operation tool 194 may indicate the ready
state using the visual indicators 198 and/or the audio indicators
200. For example, the surface operation tool 194 may indicate the
ready state by turning a light bulb visual indicator 198 yellow
and/or displaying an alphanumeric representation on an electronic
display visual indicator 198.
Once in the ready state, the control system 44 may determine
whether the arm button condition is met by determining whether the
arm button 204 on the surface operation tool 194 has been actuated
(decision block 234). As described above, the surface operation
tool 194 may transmit a start command to the electrically operated
radiation generator 40 when the arm button 204 is actuated. Thus,
when actuated, the control system 44 may determine that the arm
button condition is met and transition the electrically operated
radiation generator 40 to the output state (process block 236). In
some embodiments, the control system 44 may transition to the
output state by instructing the power supply 88 to supply
electrical power to the electrically operated radiation generator
40.
Additionally, the control system 44 may instruct the surface
operation tool 194 to indicate that the electrically operated
radiation generator 40 is in the output state (process block 238).
In some embodiments, the surface operation tool 194 may indicate
the output state using the visual indicators 198 and/or the audio
indicators 200. For example, the surface operation tool 194 may
indicate the output state by turning a light bulb visual indicator
198 red and outputting an audible alarm from a speaker audio
indicator 200. Once in the output state, the control system 44 may
continue determining whether check conditions are met and cease
output of radiation when one or more check conditions is no longer
met.
To help illustrate, one embodiment of a process 240 for controlling
operation of an electrically operated radiation generator 40 when
in the output state is described in FIG. 10. Generally, the process
240 includes determining that a radiation generator is in an output
state (process block 242), indicating the output state (process
block 244), determining a radiation metric (process block 246),
indicating the radiation metric (process block 248), determining
whether the radiation metric is less than a threshold (decision
block 250), determining status of a barrier interlock (process
block 252), indicating status of the barrier interlock (process
block 254), determining whether the barrier interlock is connected
(decision block 256), and determining whether an emergency stop
button is actuated (decision block 258).
When the radiation metric is less than the threshold, the barrier
interlock is connected, and the emergency stop button is not
actuated, the process 240 includes maintaining the electrically
operated radiation generator in the output state (arrow 260) and,
otherwise, transitioning the electrically operated radiation
generator to a standby state (process block 262). In some
embodiment, the process 240 may be implemented by executing
instructions stored in a tangible, non-transitory,
computer-readable medium, such as memory 48 of the control system
44, using processing circuitry, such as the processor 46 of the
control system 44.
Accordingly, the control system 44 may determine that the
electrically operated radiation generator 40 is in the output state
(process block 242). When in the output state, the control system
44 may instruct the electrically operated radiation generator 40 to
output radiation by instructing the power supply 88 to supply
electrical power to the electrically operated radiation generator
40 (process block 244). Thus, the control system 44 may determine
that the electrically operated radiation generator 40 is in the
output state when electrical is supplied from the power supply to
the electrically operated radiation generator 40 and/or when the
output radiation monitor 64 detects radiation output from the
electrically operated radiation generator 40.
As described above, in the output state, the control system 44 may
determine continuously and/or periodically whether check conditions
continue to be met. For example, the control system 44 may
determine whether the radiation metric threshold condition is met
by determining the radiation metric (process block 246) and
determining whether the radiation metric is less than a threshold
(decision block 250). In some embodiments, the radiation metric may
provide an indication of radiation output from the electrically
operated radiation generator 40. For example, in some embodiments,
the radiation metric may be a total count (e.g., amount of
radiation), a total count rate (e.g., amount of radiation per unit
time), integrated charge, total energy deposited, count in an
energy range, count rate in an energy range, count in a time
window, count rate in a time window, count at a pulse height, count
rate at a pulse height, ratio of counts above a discriminator
level, ratio of count rates above a discriminator level, spectrum
of counts as a function of energy, spectrum of count rates as a
function of energy, spectrum of counts as a function of time,
spectrum of count rates as a function of time, spectrum of counts
as a function of pulse height, spectrum of count rate as a function
of pulse height, spectral yield, or any combination thereof. Thus,
in such embodiments, the control system 44 may determine the
radiation metrics based at least in part on measurements determined
by the sensors 42 (e.g., output radiation monitor 64). In some
embodiments, the sensors 42 are gamma ray detectors, x-ray
detectors, neutron detectors, that are capable of determining a
count rate, a dose rate or an accumulate dose over certain time
interval. Examples of such detectors include, but are not limited
to, a Geiger Muller counter, a scintillation counter for gamma
rays, or a Bonner ball for the detection of a neutron dose rate.
Such a detector or detectors may be placed inside the radiation
barrier to determine the radiation metric near the generator or
outside of the radiation barrier where living beings are present.
When the detector is placed inside the radiation barrier, if the
radiation metric (e.g. a dose rate) is not exceeded, the radiation
threshold condition may be met. When the detector is placed outside
of the radiation barrier, a lower radiation threshold can be used
to protect the surrounding environment, including living beings. If
such threshold is not exceeded, the radiation threshold condition
may be met.
In some embodiments, the radiation metric threshold may be set
based at least in part on radiation rating of the radiation
barrier. In other words, the radiation barrier may sufficiently
block radiation resulting in a radiation metric less than the
threshold from living beings outside the radiation barrier. On the
other hand, the radiation barrier may be insufficient to block
radiation resulting in a radiation metric greater than the
threshold from living beings outside the radiation barrier. As
such, when the radiation metric is less than the threshold, the
control system 44 may determine that the radiation metric threshold
condition is met. On the other hand, when the radiation metric is
not less than the threshold, the control system 44 may determine
that the radiation metric threshold condition is not met and
transition the electrically operated radiation generator 40 back to
the standby mode (process block 262), for example, by instructing
the power supply 88 to stop supplying electrical power to the
electrically operated radiation generator 40.
The control system 44 may also instruct the surface operation tool
194 to indicate the radiation metric and/or the radiation metric
threshold (process block 248). In some embodiments, the surface
operation tool 194 may indicate value of the radiation metric by
displaying an alphanumeric representation on an electronic display
visual indicator 198. Additionally, the surface operation tool 194
may indicate when value of the radiation metric is not less than
the threshold by outputting an audible alarm from a speaker audio
indicator 200.
Additionally, the control system 44 may determine whether the
barrier interlock condition is met by determining status of the
barrier interlock 196 (process block 252) and determining whether
the barrier interlock is connected (decision block 226). In some
embodiments, the barrier interlock 196 may form a circuit when
connected. Thus, the control system 44 may determine whether
connected by polling the barrier interlock 196 to determine whether
the circuit has been formed.
As described above, the barrier interlock 196 may be connected at
the opening of a radiation barrier. In other words, the barrier
interlock 196 may be disconnected when the radiation barrier is
open and connected when the radiation barrier is closed. Thus, when
connected, the control system 44 may determine that the barrier
interlock condition is met. On the other hand, when not connected,
the control system may determine that the barrier interlock
condition is not met and transition the electrically operated
radiation generator 40 back to the standby mode (process block
262), for example, by instructing the power supply 88 to stop
supplying electrical power to the electrically operated radiation
generator 40.
The control system 44 may also instruct the surface operation tool
194 to indicate status of the barrier interlock 196 (process block
254). In some embodiments, the surface operation tool 194 may
indicate whether the barrier interlock 196 and, thus, the radiation
barrier is open or closed by displaying an alphanumeric
representation on an electronic display visual indicator 198.
Furthermore, the control system 44 may determine whether the
emergency stop button condition is met by determining whether the
emergency stop button 206 on the surface operation tool 194 has
been actuated (decision block 258). As described above, the surface
operation tool 194 may transmit a stop command to the electrically
operated radiation generator 40 when the emergency stop button 206
is actuated. Thus, when not actuated, the control system 44 may
determine that the emergency stop button condition is met. On the
other hand, when not actuated, the control system 44 may determine
that the emergency stop button condition is not met and transition
the electrically operated radiation generator 40 back to the
standby mode (process block 262), for example, by instructing the
power supply 88 to stop supplying electrical power to the
electrically operated radiation generator 40. In some embodiments,
the control system 44 may be configured in a way such that if the
radiation generator 40 does not receive a command from the control
system 44 for a predetermined period of time, it will revert to
standby mode. This provides an additional mechanism of protection
for the events such as when the control system 44 somehow becomes
unresponsive (e.g. due to a processor lock up) or the connection to
the radiation generator 40 becomes locked up. In some embodiments,
the emergency stop button may directly interrupt the power to the
radiation generator.
When each of the check conditions is met, the control system 44 may
maintain the electrically operated radiation generator 40 in the
output state to continue outputting radiation (arrow 260). It
should be appreciated that the check conditions are presented in a
particular order merely to facilitate description. In other
embodiments, the control system 44 may determine whether the check
orders are met in any order and/or in parallel. Additionally, in
other embodiments, the control system 44 may determine whether
other check conditions are met.
In this manner, the techniques described herein enable the control
system 44 to control operation of an electrically operated
radiation generator 40 when operated on the surface 16 based at
least in part on check conditions. Specifically, the check
conditions may be set so that risk of exposing living beings to
high energy radiation may be reduced when each of the check
conditions is met.
As such, the technical effects of the present disclosure include
improving control over operation of an electrically operated
radiation generator to reduce amount and/or likelihood of exposing
living beings to output radiation. In some embodiments, a control
system may use various check conditions to determine whether output
of high energy radiation is desirable. For example, when operating
downhole, the control system may check whether a start parameter is
reached, an operating parameter is reached, a stop time parameter
is reach, battery voltage is above a threshold, a password is
verified, a stop command is received, a start command is receive,
an interlock key is connected, a pressure measurement is above a
threshold, and/or a temperature measurement is above a threshold.
Additionally, when operating on the surface, the control system may
check whether a surface operation tool is connected, the surface
operation tool is operating properly, a hardware key is verified, a
barrier interlock is connected, an arm button is actuated, an
emergency stop button is actuated, and/or a radiation metric is
less than a threshold.
The specific embodiments described above have been shown by way of
example, and it should be understood that these embodiments may be
susceptible to various modifications and alternative forms. It
should be further understood that the claims are not intended to be
limited to the particular forms disclosed, but rather to cover
modifications, equivalents, and alternatives falling within the
spirit and scope of this disclosure.
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